gui-cs.Terminal.Gui/UnitTests/Views/ViewDisposalTest.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Terminal.Gui;
using Xunit;
using Xunit.Abstractions;

namespace Terminal.Gui.ViewsTests;
public class ViewDisposalTest {
#nullable enable
	Dictionary<Type, object? []?> _special_params = new Dictionary<Type, object? []?> ();
#nullable restore

	readonly ITestOutputHelper _output;

	public ViewDisposalTest (ITestOutputHelper output)
	{
		this._output = output;
	}

	[Fact]
	[AutoInitShutdown]
	public void TestViewsDisposeCorrectly ()
	{
		var reference = DoTest ();
		for (var i = 0; i < 10 && reference.IsAlive; i++) {
			GC.Collect ();
			GC.WaitForPendingFinalizers ();
		}
#if DEBUG_IDISPOSABLE
		if (reference.IsAlive) {
			Assert.True (((View)reference.Target).WasDisposed);
			Assert.Fail ($"Some Views didnt get Garbage Collected: {((View)reference.Target).Subviews}");
		}
#endif
	}

	void GetSpecialParams ()
	{
		_special_params.Clear ();
		//special_params.Add (typeof (LineView), new object [] { Orientation.Horizontal });
	}

	WeakReference DoTest ()
	{
		GetSpecialParams ();
		View Container = new View ();
		Toplevel top = Application.Top;
		var views = GetViews ();
		foreach (var view in views) {
			View instance;
			//Create instance of view and add to container
			if (_special_params.TryGetValue (view, out var param)) {
				instance = (View)Activator.CreateInstance (view, param);
			} else {
				instance = (View)Activator.CreateInstance (view);
			}

			Assert.NotNull (instance);
			Container.Add (instance);
			_output.WriteLine ($"Added instance of {view}!");
		}
		top.Add (Container);
		// make sure the application is doing to the views whatever its supposed to do to the views
		for (var i = 0; i < 100; i++) {
			Application.Refresh ();
		}

		top.Remove (Container);
		WeakReference reference = new (Container, true);
		Container.Dispose ();
		return reference;
	}

	// TODO: Consoldate this with same fn that's in AllViewsTester, ScenarioTests etc...
	/// <summary>
	/// Get all types derived from <see cref="View"/> using reflection
	/// </summary>
	/// <returns></returns>
	List<Type> GetViews ()
	{
		List<Type> valid = new ();
		// Filter all types that can be instantiated, are public, arent generic,  aren't the view type itself, but derive from view
		foreach (var type in Assembly.GetAssembly (typeof (View)).GetTypes ().Where (T => { //body of anonymous check function
			return ((!T.IsAbstract) && T.IsPublic && T.IsClass && T.IsAssignableTo (typeof (View)) && !T.IsGenericType && !(T == typeof (View)));
		})) //end of body of anonymous check function
		{ //body of the foreach loop
			_output.WriteLine ($"Found Type {type.Name}");
			Assert.DoesNotContain (type, valid);
			Assert.True (type.IsAssignableTo (typeof (IDisposable)));// Just to be safe
			valid.Add (type);
			_output.WriteLine ("	-Added!");
		} //end body of foreach loop

		return valid;
	}
}